The present invention relates to a spindle for rewinding, respooling or twisting yarn wherein the spindle core is constructed as a bobbin.
With the constant increase in spindle speeds, the accurate mounting of the bobbin on the spindle for all conditions of operation becomes increasingly difficult to achieve and maintain.
Traditionally, attachment of bobbins has been by so-called adapters, the inner diameter of the bobbin being adjusted to the spindle core or being axially secured by a bayonet lock. The required precision of the bobbins, which are made predominantly of aluminum, plastics or a combination of the two materials, can frequently not be achieved and they are thus not suitable for high speeds of spindle rotation.
A further problem is the balancing of the bobbins, as yarn imbalance jeopardizes bobbin balance, no matter how accurate it may originally have been.
As is known, with high speeds of rotation of the spindle, the bobbins must receive a tighter winding of the yarn, since as a result of the centrifugal force, the turns loosen themselves from the bobbin during rewinding or respooling. This means that the fully and tightly wound bobbin has a small bobbin diameter that becomes increasingly larger as the yarn unwinds, which leads to radial play of the bobbin. A very high degree of monitoring of the quality of the bobbins becomes necessary.
Another problem arises from the large number of bobbins used. At least three bobbins are necessary for each spindle unit, since they are variously positioned at different times at different locations, for instance, where the device is used as a spinning machine or a winding machine. The constant transport of the bobbins also does not contribute to the improvement of their quality, since damage may result.
Another disadvantage is that the boreholes of the bobbin seats become larger as a result of repeated displacement and eventually become unusable. The vibration of the spindle plays a very large role. The bobbins are applied to the spindle by means of a slide seat so that radial play must be present. This, in turn, is affected by the vibration of the spindle which also leads to enlargement of the boreholes of the bobbins, increased load on the mounting and thus premature failure of the spindles.
Since the rewinding, respooling or twisting spindle is not identical to the spool spindle, this requires a substantial additional expense for stocking spare parts and repair equipment.
In German Federal Republic Published Application OS No. 35 06 385, a bipartite spindle comprising a bobbin unit and a mounting unit is described. A spindle of this kind has disadvantages. Upon the replacement of the bobbin, the long shank of the bobbin is a disadvantage. Furthermore, a corresponding free space is required in the machine above the spindle so that the bobbin can be removed from the mounting unit and can be reinserted. This free space is not available in modern machines which are designed in compact and operator-friendly fashion.
In addition, the spindle core, which must be manufactured with high precision, is very sensitive. Slight blows, which invariably occur upon transport of the bobbin, impair the movement of the spindle and lead to premature failure of the spindle.
The precision of the fit of the spindle core to the mounting bushing can be obtained only at great financial expense. With this type of spindle design, the precision of the fit is reduced upon each change of bobbin. There is the additional factor that the bobbin shank must in each case have a slide seat, which leads to radial play. The vibrations acting on the spindle have a substantial detrimental effect on this radial play and exert a negative influence on the loading and life of the mounting.